The invention relates to improvements in apparatus for making binding elements for perforated sheets, and more particularly to improvements in apparatus for shaping and transporting such binding elements. Still more particularly, the invention relates to improvements in apparatus for imparting a predetermined shape to substantially flat strips of deformable wire binding elements for perforated sheets forming part of books, brochures, pamphlets, magazines, journals, pads, catalogues, calendars and/or other stationery or analogous products.
U.S. Pat. No. 4,873,858 granted Oct. 17, 1989 to Jones for "Manufacture of wire binding elements" discloses a machine which is designed to transform a zig-zag wire into a slotted tube that is ready for use as a binding element for accumulations of perforated sheets of paper or the like. The patented machine is provided with means for converting a flat strip of zig-zag wire into a comb like strip having a substantially C-shaped cross-sectional outline and being ready to be assembled with stacks of perforated sheets made of paper or other suitable imprinted and/or unprinted material. Once a comb-like strip is introduced into the perforations of a pile of aligned perforated sheets, the strip is closed to form a tube which confines the sheets of the pile to pivotal movements about the longitudinal axis of the tube.
A drawback of heretofore known machines and apparatus for the making of the above outlined binding elements is that the final shape of such products often departs from an optimum shape. This is attributable to tensions which develop in the binding elements as a result of deformation of substantially flat zig-zag wire strips into comb-like strips. Any departure of the configuration of comb-like strips from an optimum configuration can entail the development of problems in connection with the introduction of such imperfect strips into the perforations of piles of overlapping sheets and/or in connection with the predictability and convenience of pivoting of sheets in the thus obtained book, magazine, pad or an analogous product relative to each other.